Codec

2. The method of claim 1, wherein the predetermined number of pixels is 2, 3, 4 or 5 pixels.

3. The method of claim 1, wherein during encoding, Key frame compression comprises intra-frame compression, wherein as x increases, information on Dx frames also includes inter-frame compression from respective Dy frames.

7. The method according to claim 6, wherein the motion vectors are further refined by analyzing versions of the E Dy, C Dx and L Dy frames at increasing resolution until the motion vectors are pixel accurate.

9. The method of claim 7, wherein said candidate motion vectors for groups of pixels in the E Dy frame to the Motion Region in the C Dx frame are equal to said candidate motion vectors from the Motion Region in the C Dx frame to the group of pixels in the L Dy frame.

10. The method of claim 6, wherein said Significance is an increasing function of the absolute value of the error, with a gradient that increases as the error approaches a predetermined maximum allowed error per pixel, and falls where the error exceeds a maximum allowed error per pixel.

11. The method of claim 6, wherein if the estimate for the Motion Region based on the E Dy frame and the L Dy frame has an error greater than a predetermined value, the respective predictor is not used, wherein as x increases within a chunk, the allowable error between predicted and actual Motion Region values is an increasing function of x.

13. The method of claim 1, the method further including a method of decoding a video stream, wherein said Dx frames are encoded and decoded by referencing Transition Tables and Context; each Context code word giving its own distribution within its Transition Table.

14. The method of claim 1, wherein if one of the relevant groups of pixels from an E Dy frame or an L Dy frame touches the edge of its frame, and the other of the E Dy frame or the L Dy frame predictors suggests that the said predictor group of pixels on the edge should be off its screen and thus is Suspicious, then the E Dy frame or the L Dy frame group of pixels with the Suspicious component is excluded from the prediction of the Motion Region in the C Dx frame.

15. The method of claim 1, wherein respective Key and Delta frames from respective chunks are stored together such that Key frames are stored in a Key frame file, D1 frames are stored in a Delta 1 frame file, and so on until Dx frames, for the greatest value of x in the chunk, are stored in a Dx frame file.

17. The non-transitory machine-readable medium of claim 16, the non-transitory machine-readable medium having instructions that, when executed, cause a method of decoding a video stream to be performed, wherein said Dx Delta frames are encoded and decoded by referencing Transition Tables and Context; each Context code word giving its own distribution within its Transition Table.

19. The device of claim 18, wherein the instructions, when executed by the processor, decode a video stream, wherein said Dx Delta frames are encoded and decoded by referencing Transition Tables and Context; each Context code word giving its own distribution within its Transition Table.

20. The device of claim 18, wherein the device is a mobile phone or a personal computer.

21. The device of claim 19, wherein the device is a mobile phone or a personal computer.